The present invention relates to a structural means for mounting and demounting a light-sensitive drum used in an image-forming apparatus such as an electro-static copier or printer, a light-sensitive unit provided with the mounting/demounting structural means and an image forming device including the same light-sensitive drum unit with the same mounting/demounting structural means.
Typically, a light-sensitive body used in an image-forming apparatus such as an electro-photographic copying machine or printer is a light-sensitive drum having a supporting shaft, which can be mounted/removed to/from the apparatus by axially sliding it along the supporting shaft. The light-sensitive drum is placed rotatably in the apparatus body in such a way that it engages its supporting shaft ends with driving mechanism of the apparatus and it also engages a gear formed at a light-sensitive body flange with a driving gear of the apparatus""s driving mechanism. This mounting/demounting structure requires the user to mount or demount the light-sensitive body by positioning the ends of its shaft with respect to the driving mechanism of the apparatus. The use of this structure results in elongation of the light-sensitive body and increasing its weight. The light-sensitive drum unit cannot be easily handled.
Several structural means for mounting and demounting a light sensitive drum in a conventional image-forming device such as a conventional electro-static copying machine or printer have been proposed. Typically, Japanese Laid-Open Utility Model Publication No. 1-57772 discloses a light-sensitive drum of the type that a light-sensitive unit consisting of a light-sensitive drum and a cleaning device unitarily formed with a supporting member is separately formed from an electro-charging device and the drum is mounted downward onto or removed upward from the supporting member in the image-forming device. Japanese Laid-Open Patent Publication No. 63-267989 discloses an image forming device in which a light sensitive drum can be moved along a horizontal guide rail attached to a supporting member of the light sensitive drum to a given position and fixed thereat.
The first prior art (Japanese Laid-Open Utility Model Publication No.1-57772) describes a light-sensitive unit consisting of a light-sensitive drum and a cleaning device integrally formed thereon, which is supported by a supporting member having a concave section opposite to an end face of the drum and being perpendicular to an axial line of the end face of the drum. This concave section allows the user to easily mount and remove the light-sensitive drum (downward) from the upper side of the device where an electrically charging device is located.
The second prior art (Japanese Laid-Open Patent Publication No.63-267989) teaches a guide rail that is swingably attached to a supporting member of a light-sensitive drum and, when mounting or demounting the light-sensitive drum, can be turned from a normal vertical position to a horizontal position. In the horizontal state, it can rotate and carry the supporting shaft of the light-sensitive drum along the guide rail. This allows the user to easily mount the light-sensitive drum in the horizontal state in the device. Furthermore, turning the guide rail actuates means for detaching the supporting shaft from a driving mechanism, making easier the removal of the light-sensitive drum.
In the light-sensitive drum unit unitarily constructed of a light-sensitive drum, an electrically charging device and a cleaning device, the light-sensitive drum must be mounted or removed with care not to damage by collision the working surfaces of the drum, the charger and a blade of the cleaning device. The light-sensitive drum can be easily downsized as compared with the charger, developing device, transferring device and cleaning device surrounding the drum. However, it is difficult for a user to mount or remove a small drum due to irrevocable interference between the frame and own fingers.
The prior art disclosed in Japanese Laid-Open Utility Model Publication No.1-57772 can mount/demount the light-sensitive drum from the upper side of a light-sensitive unit separately formed from an electrostatic charger but cannot realize the same in a light-sensitive unit constructed unitarily with the charger. Namely, the prior art requires the provision of a separate charger that must be replaced to a refuge position before mounting/demounting the light-sensitive drum. This requires the user to do additional complicated work.
The prior art disclosed in Japanese Laid-Open Patent Publication No. 63-267989 merely refers to mounting and demounting of a light-sensitive drum in a horizontal state and does not consider devices disposed around the drum. Especially for the light-sensitive unit formed unitarily with the charger and the cleaning device having a cleaning blade, it is essential to take care not to damage, by colliding the drum and charger, the light sensitive surface of the drum and cleaning edge of the cleaning blade when mounting/demounting the drum from the unit. The prior art disclosed in Japanese Laid-Open Patent Publication No. 63-267989 describes merely the fact that the light-sensitive drum is placed and removed in the horizontal state. There is no description relating how to mount the light-sensitive drum with respect to the surrounding devices. No description is found whether the drum can be replaced without previously removing the charger and with no fear of damaging the working surface of the drum and grids of the charger.
The present invention relates to structural means for mounting and demounting a light-sensitive drum in an image-forming device such as a copying machine and a printer, a light-sensitive body unit provided with the same structural means and an image-forming device provided with the same light-sensitive body unit with the same structural means. Specifically, this invention refers to a light-sensitive drum mounting/demounting structure allowing one to mount the drum in a frame of a light-sensitive drum with no fear of damaging its light-sensitive body; a light-sensitive unit that can integrally support a cleaning device, an electrically charging device and a light sensitive drum and allows at least the light-sensitive drum to be removably mounted on its frame; and a image forming device incorporating the light-sensitive body unit.
An object of the present invention is to provide a simple structure for easily mounting and demounting a light-sensitive drum with no need of demounting an electrically charging device in advance and with no fear of damaging the light-sensitive surface of the drum and a cleaning blade edge.
Another object of the present invention is to provide a structure for easily mounting and demounting a light-sensitive drum in and from a frame of a light-sensitive unit by holding the drum with fingers.
A further object of the present invention is to provide a structure for mounting/demounting a light-sensitive drum in/from a frame of a light-sensitive body unit without decreasing the strength of the supporting member and increasing the size thereof.
The above-mentioned drawbacks of the prior arts are solved by the following technical means provided by the present invention.
The first technical means is a light-sensitive drum mounting/demounting structure for removably supporting in its frame a light-sensitive drum bearing a latent electrostatic image formed on its cylindrical surface, which structure is provided with regulating means for preventing the light-sensitive surface of the drum from contacting the other members arranged around the drum when mounting the latter into the frame.
The second technical means is the light-sensitive drum mounting/demounting structure as defined by the first technical means, which is featured by the frame having a pair of holders disposed opposite to each other with the drum between them and supporting the respective ends of the drum shaft and by use of the regulating means for restricting the movement of the supporting shaft.
The third technical means is the light-sensitive drum mounting/demounting structure as defined by the second technical means, which is featured in that one holder of the paired holders has a throughout hole made therein for inserting the supporting shaft of the light-sensitive drum and the regulating means is a bearing portion formed as an axially protrusion of the inner wall of the through hole (cylinder) to receive the end of supporting shaft of the light-sensitive drum.
The fourth technical means is a light-sensitive drum mounting/demounting structure for removably supporting in its frame the light-sensitive drum bearing a latent electrostatic image formed on its external cylindrical surface, which structure is provided with a finger-relief notch formed in the frame portion adjacent to a space through which the light-sensitive drum is mounted/removed in/from the frame.
The fifth technical means is the light-sensitive drum mounting/demounting structure as defined by the third or fourth technical means, which is featured in that one of the paired holders has a stopper removably fit in its side wall thereof and a guide formed in the same place with the stopper removed for guiding the supporting shaft of the light-sensitive drum to be mounted in the same holder.
The sixth technical means is a light-sensitive body unit provided with any one of the light-sensitive drum mounting/demounting structures of the technical means 1 to 5.
The seventh technical means is a light-sensitive unit having a frame for unitarily holding a cleaning device having a blade for scrapping off toner from the light-sensitive drum surface, an electrically charging device and an at least removable light-sensitive drum, which unit is so constructed that a frictional force acting on the cleaning blade edge being in contact with the cylindrical surface of the light-sensitive drum when mounting the latter in the frame is directed toward the cleaning edge from the supporting member and the light-sensitive drum is mounted from the direction where it cannot touch the electrically charging device.
The eighth technical means is a light-sensitive body unit having a frame for unitarily holding a cleaning device having a blade for scraping toner from the light-sensitive drum surface, an electrically charging device and an at least removable light-sensitive drum, which is so constructed that the light-sensitive drum is axially inserted at its one end in an holder disposed at one end of the frame and is sideward inserted at the other end in a holder disposed at the other end by horizontally turning the latter end of the drum relative to its former end.
The ninth technical means is a light-sensitive body unit as defined by any one of the technical means 7 and 8, which is featured in that its frame has a base to be placed on a working surface in such a way that light-sensitive drum can be mounted or removed from the upper diagonal direction.
The tenth technical means is a light-sensitive body unit as defined by the technical means 8, which is featured in that the holder disposed at one end of the frame supports one end of the light-sensitive drum and a locating block of an image-forming device when the light-sensitive body unit is mounted in the image-forming device.
The eleventh technical means is an image-forming device provided with a light-sensitive drum mounting/demounting structure defined by any one of the technical means 1 to 5 or a light-sensitive body unit defined by any one of the technical means 6 to 10.